$\begingroup$Hi, @Nir! So, you want to set hotend temperature, and wait until it is warm before printing (at the end of start.gcode)? I generally doubt you really need to explicitly set a delay - it is basically a hack to overcome (not fix) the problem!$\endgroup$
– Tormod HaugeneFeb 7 '16 at 21:44

$\begingroup$@LarsPötter That should be an answer, not a comment!$\endgroup$
– Tom van der ZandenFeb 7 '16 at 21:52

$\begingroup$In my end-G-code, I shut off the hot end, and wait several minutes before shutting off the fan. I was getting communications timeout errors and the fan would never actually shut off from the code (using Monoprice Select Mini with Octoprint). If this occurs for you before the print, it will not print at all. I resolved it by simply breaking it up unto a series of shorter delays.$\endgroup$
– mbmcavoyMar 1 '18 at 19:57

$\begingroup$For cncjs, the command is G4 P0.5 for half a second, for example. i.e. it's a float, not an int.$\endgroup$
– Gavin SimpsonMay 28 at 6:55

On M190 S35, the nozzle is still on the low position (1.2mm), then goes to 4mm then waits for the extruder temperature Ex. 195°C; when the extruder reach the 195°C for 10 seconds then the printers starts to print going the nozzle to 0.22mm while the nozzle reach the second temperature of 210°C. On This time its allow me to clean the nozzle and normalize the temperatures for a good prints.

Note:
To avoid the nozzle stays many time on low position (1.2mm) normally I preheat the bed at 35°C. some times to heat the bed takes a longer time than heating the nozzle. This is the main reason that I prefer to preheat the printer.